Dear Mr. Bard,
Thank you for posting your question on History Hub!
We entered the keyword “Korean War” into the National Archives Catalog to search for any records relating to your inquiry in the Records of the Office of the Provost Marshal General (Record Group 389). The search produced the following results.
Further, we searched for “Korean War” and “POW.” The search results can be found here. Finally, a search in the National Archives Catalog for “Korean War,” and “UN,” and “POW” produced the following results.
Also, we suggest reviewing Reference Information Paper 103 titled “National Archives Records Relating to the Korean War” by Rebecca L. Collier as it contains a lot of important information on the subject. In addition, the National Archives has a webpage relating to Korean War records. You might find it useful as it provides links to several valuable resources.
We hope this information is helpful. Best of luck with your research!